Welcome back to Mactutors Lisp column! By the time this issue is printed Experlisp from Expertelligence should be released. For the many of you out there who have yet to see this new version of Lisp, the Lisp Listener Window shall present its first description of Experlisp along with more descriptions of Common Lisp procedures.

Experlisp

Experlisp consists of a Listener Window, an editor and a compiler. The Listener Window can act as an interpreter, however it only operates on one line of code. One can use it to try out a simple list and see what the list will do. For multiple line lists or programs one must write the code using the editor. The editor has its own window or windows, which are called Edit Buffers when untitled. It can have more than one Edit Buffer open at the same time just as Macdraw and MSWord. The editor consists of all the standard editing operations that appear in most Macintosh text editing programs. Cutting and pasting between files is extremely easy and fast because multiple lists can be displayed simultaneously. After one types in their lists the Compile menu provides the choice of compiling and executing a selected group of code or the entire program. When either is selected the compiler kicks in and compiles the Lisp code to 68000 machine code. It happens rather quickly and when completed, the program is initiated. All interaction with the program then takes place in the Listener Window, unless programmed otherwise. A screen dump of the Experlisp display is shown in Figure 5. Please note that this was taken using the prereleased version. The released version, Im told does not include the Help or Output menus on the menu bar. Also the Run menu was changed to Compile.

Figure 2. Two Dimensional Bunny Graphics

Experlisp is a combination of three worlds. First, as I have already mentioned last month, Experlisp is based on the Common Lisp standard described by Winston and Horns Lisp 2nd edition. It also contains elements from Zetalisp, the version of Lisp used on Symbolics workstations. This is no surprise since Experlisp was developed on a Symbolics machine. Finally (I saved the best part), Experlisp can access the Macintosh toolbox. In fact one must use the same syntax as shown in Inside Macintosh, the Mac developers Bible. Experlisp has the capability to open and close windows, define and create menus on the menu bar and generate all the Macintosh graphics primitives. Experlisp also contains all the graphics features found in Experlogo (also developed by Expertelligence). One can generate turtle graphics as in any logo, however Experlogo and Experlisp use the term Bunny graphics. This is characterized by instructions which tell a Turtle (from the original Logo, which moved a mechanical device which looked like a turtle) or Bunny to move in specific directions. Bunny graphics can be two dimensional, three dimensional or spherical. Spherical is not your typical form of graphics. In spherical graphics the lines seem to be drawn upon a three dimensional globe. Figure 1 is a box drawn repeatedly while rotated in a circle in 2D, figure 2 is the same box pattern in 3D and figure 3 is in spherical.

Figure 3. Three Dimensional Bunny Graphics

Figure 4. Spherical Bunny Graphics

Next month I will discuss how the above figures were generated.

One of the most exciting features about Experlisp is its speed. It is fast. The program operates at a speed comparable to programs written in assembly language and Forth. However, Lisp is significantly easier to learn and it does handle symbol manipulation as we shall eventually see. As I mentioned last month, one might question its usability in AI applications due to the memory size of the Mac. Expertelligence informs me that the Lisp program code is treated in a virtual manner typical to the Macintosh. Code is loaded when needed. Therefore, the size of your program depends upon disk space rather than RAM. The memory limitations do not effect the program size, instead they effect the size of a function. In Lisp one can define a function similar to the way Forth generates its own syntax. [Note the use of reverse polish notation, common to Forth code.] For example:

(DEFUN AVERAGE (W X Y Z)
(/ (+ W X Y Z) 4))

The above defines the word AVERAGE as the average of a four argument list. Whenever AVERAGE is used followed by four numbers it will generate the mean of the numbers, as shown below:

(AVERAGE 7 3 9 5)
;6

Experlisp can allow functions up to 250Kbytes in size! Note that my example didnt generate one full Kbyte of code.

It sounds great, however like all things there are imperfections. Even though the compiler generates 68000 code there is presently no way to execute that code other than via the Experlisp editor and compiler. Stand-alone applications in Experlisp might become a reality soon however, according to what I have been told by Expertelligence. The manual states that Experlisp 2.0 will be a much expanded..developers version. There is also the question of debugging facilities. In MacPascal and MSBasic 2.0 there are extremely useful tracing commands which show the programmer exactly what the code is doing every step of the way during execution. Unfortunately, Experlisp does not have that. However, that is no surprise since both Macpascal and MSBasic 2.0 are both completely interpreted languages. Remember, Experlisp is compiled. Error messages are displayed in the Listener Window during compilation. Additionally, Experlisp does provide us with a TRACE Macro which shows the values of a function both before and after execution as well as the ability to break during execution and examine values. Although, it would be useful to see more then just the effects on arguments at the function level. We hope to provide the code for more indepth tracing in Experlisp sometime in a future installment of the Lisp Listener Window. There is another disadvantage for which there is no easy answer; Experlisp works only on a Macintosh 512 or the XL. Sorry, the 128K Mac is too skinny. If this gets you down, try to be patient. The upgrade will more than likely continue to go down in price. One last unfortunate note is the cost. Experlisp will list price at $500.00. This high cost, Im told, was due to the development costs of Experlisp and its copy protection scheme. It will (eventually) be protected using a small piece of hardware which connects between the keyboard and the Mac. If Experlisp becomes as popular as I think it will, this number will probably also come down. At this time Experlisp is a good investment for someone who is very serious about learning and using Lisp for both AI and nonAI programming tasks regardless of the above disadvantages. If I thought otherwise I would not be writing this column!

Last month I mentioned that I was skeptical about whether or not we might be able to produce a serious AI application on the Mac. This month, after learning more about Experlisp, Im willing to stick my neck out a bit and say that I feel that a relatively serious application is possible. However, the application will probably be a limited expert system using shallow production rules as opposed to indepth semantic networks. One of the advantages to Experlisp is the ease in which one may build the applications user interface. That in itself places the Mac in the running for real applications using Lisp. Although, serious AI development will require at least a hard disk drive along with the external drive. Time will tell if Ill eat these words.

More Lisp Procedures

We finished last week with brief descriptions of the CAR and CDR procedures. The procedures are used in taking lists apart. One can nest these procedures so that longer lists may be dissected. For example:

All lists following the ; and in bold are output from the computer) These CARs and CDRs can be combined into one procedure. The above can also be written as follows:

(CADDR (BEANS PEAS CORN CARROTS))
;(CORN)

Each A within the C and the R represents a CAR, while each D represents a CDR. Any combination is possible. In Experlisp a depth of four combinations are allowed. That is, CxxxxR, CxxxR or CxxR, while x=A or D.

Other procedures are used in adding new arguments to a list or for making new lists. These are called Construct lists. The CONS function (short for constructor) puts a new argument at the beginning of a list.

For example:

(CAR (CONS x (y z)))
;x

The CONS adds the x to (y z ) making (x y z) from which the CAR extracted the x.

The APPEND function puts the arguments from given lists into one new list. For example:

(APPEND (A B C) (D E F))
;(A B C D E F)

The LIST function takes the arguments from given lists or entire lists and puts them into a new list. For example;

(LIST (A B C) (D E F) (G H I))
;((A B C) (D E F) (G H I))

The actual value of the LIST function is not apparent since I have not yet discussed assigning values to symbols. One way to perform this assignment is with the SETQ function. SETQ places the value or values of the second argument following the SETQ function and assigns it or them to the first argument. The following example demonstrates this:

After evaluating the first list the symbol VEGETABLES represents (PEAS BEANS CARROTS).When one types the assigned symbol into the Listener Window (after compiling and running the above list) the assigned values are displayed. Of course this example is extremely simple. In coming installments the SETQ function will be used with more interesting examples which will better illustrate the object oriented qualities of Lisp. Getting back to the LIST function, the following example shows its real strength in relation to APPEND and CONS:

If you have obtained a prereleased version of Experlisp (v0.1), note that the MIN and MAX procedures are not functional. The nested CARs and CDRs wont work either. You might have also noticed that sometime at the end of March you could not get Experlisp v0.1 to boot up. Expertelligence has something in the code that checks for the date. Beyond the release date (March 31st) the prerelease should not be functional. Unless of course one worked around the current date (set your calender back!). There are other problems associated with using the prerelease. The prerelease manual is actually only an incomplete reference manual and does not contain specific details of Experlisp. Also there is some mixture between Zetalisp and the Common Lisp standard. These combinations are not apparent in the prereleased manual, but are in the release. Obviously, one should not gamble on using a prereleased Experlisp for any kind of programming efforts outside of hacking for fun. If you are without a version of Experlisp but you do have Xlisp some of the above described procedures will work. Type them in as shown, but remember to use lowercase.

Next month the Lisp Listener Window will include sample source listings for generating bunny graphics, windows, menus and various Macintosh toolbox commands.

Community Search:

MacTech Search:

Software Updates via MacUpdate

EtreCheck 3.1.5 - For troubleshooting yo...

EtreCheck is an app that displays the important details of your system configuration and allow you to copy that information to the Clipboard. It is meant to be used with Apple Support Communities to... Read more

WALTR 2 2.0.8 - $39.95

WALTR 2 helps you wirelessly drag-and-drop any music, ringtones, videos, PDF, and ePub files onto your iPhone, iPad, or iPod without iTunes. It is the second major version of Softorino's critically-... Read more

Carbon Copy Cloner 4.1.12 - Easy-to-use...

Carbon Copy Cloner backups are better than ordinary backups. Suppose the unthinkable happens while you're under deadline to finish a project: your Mac is unresponsive and all you hear is an ominous,... Read more

Dropbox 16.3.27 - Cloud backup and synch...

Dropbox is an application that creates a special Finder folder that automatically syncs online and between your computers. It allows you to both backup files and keep them up-to-date between systems... Read more

Microsoft OneNote 15.29 - Free digital n...

OneNote is your very own digital notebook. With OneNote, you can capture that flash of genius, that moment of inspiration, or that list of errands that's too important to forget. Whether you're at... Read more

Spotify 1.0.44.100. - Stream music, crea...

Spotify is a streaming music service that gives you on-demand access to millions of songs. Whether you like driving rock, silky R&B, or grandiose classical music, Spotify's massive catalogue puts... Read more

SpamSieve 2.9.27 - Robust spam filter fo...

SpamSieve is a robust spam filter for major email clients that uses powerful Bayesian spam filtering.
SpamSieve understands what your spam looks like in order to block it all, but also learns what... Read more

VueScan 9.5.62 - Scanner software with a...

VueScan is a scanning program that works with most high-quality flatbed and film scanners to produce scans that have excellent color fidelity and color balance. VueScan is easy to use, and has... Read more

Fantastical 2.3.2 - Create calendar even...

Fantastical 2 is the Mac calendar you'll actually enjoy using. Creating an event with Fantastical is quick, easy, and fun:
Open Fantastical with a single click or keystroke
Type in your event... Read more

PCalc 4.4.4 - Full-featured scientific c...

PCalc is a full-featured, scriptable scientific calculator with support for hexadecimal, octal, and binary calculations, as well as an RPN mode, programmable functions, and an extensive set of unit... Read more

Latest Forum Discussions

Galaxy on Fire 3 - Manticore brings the series back for another round of daring space battles. It's familiar territory for folks who are familiar with the franchise. If you've beaten the game and are looking to broaden your horizons, might we... | Read more »

The best apps for your holiday gift exch...

What's that, you say? You still haven't started your holiday shopping? Don't beat yourself up over it -- a lot of people have been putting it off, too. It's become easier and easier to procrastinate gift shopping thanks to a number of apps that... | Read more »

MyTona, based in the chilly Siberian city of Yakutsk, has brought a little festive fun to its hidden object game Seekers Notes: Hidden Mystery. The Christmas update introduces some new inhabitants to players, and with them a chance to win plenty of... | Read more »

PINE GROVE 1.0
Device: iOS Universal
Category: Games
Price: $1.99, Version: 1.0 (iTunes)
Description:
A pine grove where there are no footsteps of people due to continuous missing cases. The case is still unsolved and nothing has... | Read more »

Niantic teases new Pokémon announcement...

After rumors started swirling yesterday, it turns out there is an official Pokémon GO update on its way. We’ll find out what’s in store for us and our growing Pokémon collections tomorrow during the Starbucks event, but Niantic will be revealing... | Read more »

3 reasons why Nicki Minaj: The Empire is...

Nicki Minaj is as business-savvy as she is musically talented and she’s proved that by launching her own game. Designed by Glu, purveyors of other fine celebrity games like cult favorite Kim Kardashian: Hollywood, Nicki Minaj: The Empire launched... | Read more »

Clash of Clans is getting its own animat...

Riding on its unending wave of fame and success, Clash of Clans is getting an animated web series based on its Clash-A-Rama animated shorts.As opposed to the current shorts' 60 second run time, the new and improved Clash-A-Rama will be comprised of... | Read more »

Leaks hint at Pokémon GO and Starbucks C...

Leaked images from a hub for Starbucks employees suggests that a big Pokémon GO event with the coffee giant could begin this very week. The images appeared on Reddit and hint at some exciting new things to come for Niantic's smash hit game.
| Read more »

Price Scanner via MacPrices.net

Never Settle for Low Performing Wifi With iOS...

AppYogi Software has announced the release of WiFi Signal Strength Status App 1.0, the company’s new utility developed exclusively for macOS. WiFi Signal Strength Status App features a unique, single... Read more

DietSensor, Inc., a developer of smart food and nutrition applications designed to fight diabetes and obesity and help improve overall fitness, has announced the launch of its DietSensor app for... Read more

Best Buy has dropped their price on the 64GB Apple TV to $159.99 including free shipping. That’s $40 off MSRP.
32GB Apple TVs are on sale right now for $98 on Sams Club’s online store. That’s $51 off... Read more

12-inch Retina MacBooks, Apple refurbished, n...

Apple has restocked a full line of Certified Refurbished 2016 12″ Retina MacBooks, now available for $200-$260 off MSRP. Refurbished 2015 models are available starting at $929. Apple will include a... Read more

Apple has Certified Refurbished 13″ MacBook Airs available starting at $849. An Apple one-year warranty is included with each MacBook, and shipping is free:
- 13″ 1.6GHz/8GB/128GB MacBook Air: $849 $... Read more

Apple refurbished iMacs available for up to $...

Apple has Certified Refurbished 2015 21″ & 27″ iMacs available for up to $350 off MSRP. Apple’s one-year warranty is standard, and shipping is free. The following models are available:
- 21″ 3.... Read more

MacTech is a registered trademark of Xplain Corporation. Xplain, "The journal of Apple technology", Apple Expo, Explain It, MacDev, MacDev-1, THINK Reference, NetProfessional, Apple Expo, MacTech Central, MacTech Domains, MacNews, MacForge, and the MacTutorMan are trademarks or service marks of Xplain Corporation. Sprocket is a registered trademark of eSprocket Corporation. Other trademarks and copyrights appearing in this printing or software remain the property of their respective holders. Not responsible for typographical errors.

All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.